draw: Replace pointer arithmetic with cast.

Using uintptr_t as intermediate type for pointer -> integer conversions is
easier to understand and does not cause any size mismatch warnings.
uintptr_t is part of C99, and we already provide a suitable replacement
definition for all platforms we care about.

diff --git a/src/gallium/auxiliary/draw/draw_pt_elts.c b/src/gallium/auxiliary/draw/draw_pt_elts.c
index b7780fb..88f4d9f 100644 (file)
--- a/src/gallium/auxiliary/draw/draw_pt_elts.c
+++ b/src/gallium/auxiliary/draw/draw_pt_elts.c
@@ -54,7 +54,8 @@ static unsigned elt_ubyte( const void *elts, unsigned idx )
 
 static unsigned elt_vert( const void *elts, unsigned idx )
 {
-   return (const ubyte *)elts - (const ubyte *)NULL + idx;
+   /* unsigned index is packed in the pointer */
+   return (unsigned)(uintptr_t)elts + idx;
 }
 
 pt_elt_func draw_pt_elt_func( struct draw_context *draw )